Hi, On 27-05-16 13:10, Peter Wu wrote:
On Wed, May 25, 2016 at 04:55:35PM +0300, Mika Westerberg wrote:On Wed, May 25, 2016 at 12:53:01AM +0200, Peter Wu wrote:Since "PCI: Add runtime PM support for PCIe ports", the parent PCIe port can be runtime-suspended which disables power resources via ACPI. This is incompatible with DSM, resulting in a GPU device which is still in D3 and locks up the kernel on resume.Mirror the behavior of Windows 8 and newer[1] (as observed via an AMLi debugger trace) and stop using the DSM functions for D3cold when power resources are available on the parent PCIe port. [1]: https://msdn.microsoft.com/windows/hardware/drivers/bringup/firmware-requirements-for-d3cold Signed-off-by: Peter Wu <[email protected]> --- drivers/gpu/drm/nouveau/nouveau_acpi.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c index df9f73e..e469df7 100644 --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c @@ -46,6 +46,7 @@ static struct nouveau_dsm_priv { bool dsm_detected; bool optimus_detected; bool optimus_flags_detected; + bool optimus_skip_dsm; acpi_handle dhandle; acpi_handle rom_handle; } nouveau_dsm_priv; @@ -212,8 +213,26 @@ static const struct vga_switcheroo_handler nouveau_dsm_handler = { .get_client_id = nouveau_dsm_get_client_id, }; +/* Firmware supporting Windows 8 or later do not use _DSM to put the device into + * D3cold, they instead rely on disabling power resources on the parent. */ +static bool nouveau_pr3_present(struct pci_dev *pdev) +{ + struct pci_dev *parent_pdev = pci_upstream_bridge(pdev); + struct acpi_device *ad;Nit: please call this adev instead of ad.Will do.+ + if (!parent_pdev) + return false; + + ad = ACPI_COMPANION(&parent_pdev->dev); + if (!ad) + return false; + + return ad->power.flags.power_resources;Is this sufficient to tell if the parent device has _PR3? I thought it returns true if it has power resources in general, not necessarily _PR3. Otherwise this looks okay to me.It is indeed set whenever there is any _PRx method. I wonder if it is appropriate to access fields directly like this, perhaps this would be more accurate (based on device_pm.c): /* Check whether the _PR3 method is available. */ return adev->power.states[ACPI_STATE_D3_COLD].flags.valid; I am also considering adding a check in case the pcieport driver does not support D3cold via runtime PM, what do you think of this? if (!parent_pdev) return false; /* If the PCIe port does not support D3cold via runtime PM, allow a * fallback to the Optimus DSM method to put the device in D3cold. */ if (parent_pdev->no_d3cold) return false; This is needed to avoid the regression reported in the cover letter, but also allows pre-2015 systems to (still) have the D3cold possibility. Out of curiosity I looked up an pre-2015 laptop (found Acer V5-573G, apparently from November 2013, Windows 8.1) and extracted the ACPI tables from the BIOS images. BIOS 2.28 (2014/05/13) introduces support for power resources on the parent devicea(\_SB.PCI0.PEG0._PR3 and a related NVP3 device) when _OSI("Windows 2013") is true. (This is added as alternative for the old DSM interface.) Maybe 2014 is also an appropriate cutoff date? I wonder if it is feasible to detect firmware use of _OSI("Windows 2013") and use that instead of the BIOS year.
It is definitely possible to check if the firmware uses _OSI("Windows 2013")
we do something similar to check for windows-8 ready laptops in the backlight
code, see acpi_osi_is_win8() in drivers/acpi/osl.c, or if you actually
want to test for Windows 8 or newer, just use acpi_osi_is_win8() :)
Regards,
Hans
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